Man has used wind energy for a long time, perhaps as long as 2000 years. However, with more modern times and rapidly developing technologies, the use of wind energy as a convenient and usable form of energy has been largely ignored. Thus during the rapid industrialization of the late 18th and 19th centuries other forms of energy to supply power for industry have been utilized with little or no attention given to the possible uses of wind energy.
However, in recent times, primarily due to the ever-increasing public awareness of energy shortages, the possible use of wind energy has been given additional attention.
There are two basic types of wind turbines or windmills, the two terms being utilized herein interchangeably. One of these is the vertical axis windmill or turbine which will accept wind from any direction with the power being typically available at the ground level. The other is a horizontal axis machine perhaps best typified by the familiar "old Dutch windmill." This invention relates to an improvement in the vertical axis windmill.
Most problems with vertical axis type wind turbines have been with the wind rotor for the wind turbine which travels at very high rates of speed during times of strong wind. Thus, for example, a high speed wind rotor with straight, rigid blades parallel to the axis of rotation is subjected to very high bending moments due to centrifugal forces and often necessitates extensive bracing to withstand the high forces. On the other hand, perfectly flexible blades on a high speed vertical axis rotor are undesirable in that their wind catching ability is greatly reduced and correspondingly their efficiency in conversion of wind energy into other forms of energy is greatly inhibited. Thus one problem which has existed in the prior art is that wind rotors having blades of the most efficient wind catching structure cause the most stress forces on the frame for the wind rotor and in extreme situations may cause damage thereto. On the other hand, blade configurations which cause the least stress to the turbine structure in turn are the least efficient in wind energy gathering ability and transfer of that wind energy in an efficient manner to other useful energy sources.
Accordingly, one object of this invention is to provide an improved wind rotor for a vertical axis wind turbine which makes very efficient use of the available wind energy.
Another object of this invention is to provide a wind rotor for a vertical axis wind turbine which in spite of its highly efficient performance, will not operate during strong winds at such high speeds as to create centrifugal forces having the potential for damaging the overall structure of the wind turbine.
Yet another object of this invention is to provide a wind rotor for a vertical axis wind turbine with the rotor having concave surfaced wind catching members and convex surfaced wind deflecting members in order to provide for extremely efficient wind energy transfer on the one hand and correspondingly extremely efficient air flow with little resistance past the wind deflecting convex surfaces.
Still another object of this invention is to provide a wind rotor with the rotor having wind break gaps therein in order to prevent excess damage to the wind turbine during periods of excessively high winds.
Yet another object of this invention is to provide all of the above objects in a structure which is simple to make, and can efficiently and economically be manufactured and sold.
The method of accomplishing these and other objects of the invention will be apparent from the following description of the invention.